Bishop of Sodor and Man from 1755 until his death in 1772, under whom the Bible was first put into Manx.

He came to the see by an unusual route. The patronage lay with the Duke of Atholl, who waived his right of nomination and referred the choice to the bench of English bishops, asking them to point out a man worthy of wearing the mitre which Bishop Wilson had adorned. They recommended Dr Mark Hildesley, rector of Hitchin in Hertfordshire, unanimously. The sources do not agree on the date of his consecration: one gives 25 March 1755, another 22 April of that year.

He knew what he was following. On succeeding Wilson he wrote that he was aware it is sometimes said that a person succeeds with disadvantage to an office which has been filled by a predecessor of note, and went on in that vein at some length.

The translation was his work. Manx people had no part of the Bible in their own tongue. The Gospels of Mark, Luke and John and the Acts of the Apostles had been translated in Wilson's time but never published, and the Gospel of Matthew was printed in 1748. Hildesley divided the remaining task among his clergy, and while it went forward he set some of them to translate the Prayer Book as well. The Prayer Book appeared in 1765 and the Bible in 1775, three years after his death.

He was at Ramsey for one of the more dramatic days of the century. When Thurot's squadron was taken in the bay in 1760, the people of the west side could hear the guns, and a Manx ballad has the Bishop with all his train among those listening. A piece of the Belle Isle's bowsprit is said to have come ashore on the Bishop's own ground. Hildesley wrote afterwards to Dr Monsey, dryly correcting the accounts then circulating: they might as well have given the bishop the honour of having preached Thurot's funeral sermon, since he did preach at Ramsey on the very day the body was supposed to have been buried there.

His own family had been clergy before him. He was the son of Mark Hildesley, rector of Murston and afterwards of Witton in Huntingdonshire, and grandson of a Counsellor Mark Hildesley. His mother Avis bore sixteen children who lived to be baptised. His wife Elizabeth, born Stoker, died on 27 February 1763. The monument at Kirk Michael records his own death on 2 December 1772, in the seventeenth year of his consecration, aged seventy-four.